This is one of those stories that goes around in certain communities. I don't know if it's true or not; it may well be. I've heard of it several times, but only ever second- or third-hand. I've also heart it's happened to more than one company. The thing is, you can't really verify this sort of stuff: if it's true, whoever developed it would throw its full weight behind it and hit as many targets as possible. It would probably be under tight investigation by some three-letter. Companies also probably wouldn't want to disclose this. I don't know if It's not unreasonable to hypothesize N. Korea or Iran put together a kit, though they'd probably relegate it to a certain stack (too much technical debt otherwise).

Of course, it's also possible it's not, and I wonder if that's more likely. Every industry has such stories; maybe this is the white whale of forensics.